Field of the Invention
The present invention relates to an array substrate, a method for inspecting an array substrate, and a method for inspecting a display panel.
Description of the Background Art
A display panel is provided with an array substrate. The array substrate has a glass substrate on which a display circuit is located to form display portions. An array inspection includes a technique, which has been known, of writing electrical charge on each of pixels forming the display portion and reading the electrical charge maintained in the pixels to inspect gate signal lines and source signal lines of semiconductor switching elements for breaks and short circuits, the pixels for defects, and the semiconductor switching elements for failures. The array inspection typically causes each of inspection needles (probes) to collectively come into contact with an inspection terminal located at each of the gate signal lines and each of the source signal lines and then inputs an inspection signal to each of the gate signal lines to successively operate the semiconductor switching elements formed at each intersection while inputting an inspection signal to each of the source signal lines to write the electrical charge on the pixels.
In general, terminals (mounting terminals) for mounting semiconductor chips and flexible print cables (FPCs) in the following steps may be used as the inspection terminals, or the inspection terminals may be provided separately near the terminals. The inspection terminals are provided in this manner, allowing for the inspection of the display circuit in a range of the terminals to the display portion.
In the technique of inspecting the array substrate as described above, the inspection terminals connected to the plurality of gate signal lines and the plurality of source signal lines are probed individually, so that a probe unit (unit including a plurality of probes mounted thereon) serving as an inspection jig needs to be manufactured for each of types in which the inspection terminals are disposed differently.
Meanwhile, a panel lighting inspection is performed in a panel state. The panel state is a state in which the display panel including the array substrate and a display element is formed. For example, liquid crystals are sealed between the array substrate and a counter substrate to form a liquid crystal display panel. The panel lighting inspection displays an image on the display panel and determines whether the image is properly displayed. For example, the panel lighting inspection similar to the technique of inspecting the array substrate probes all of the inspection terminals of the source signal lines and the gate signal lines, inputs the inspection signals to the source signal lines and the gate signal lines, and then checks the image to determine whether each of the pixels performs a correct display.
In recent times, a circuit capable of collectively controlling the plurality of gate signal lines and the plurality of source signal lines is provided beforehand on the array substrate, and a collective lighting inspection that enables a specific display with the extremely small number of probes is also applied.
Unlike the inspection technique of individually probing the inspection terminals each located at the plurality of gate signal lines and the plurality of source signal lines, the technique of the collective lighting inspection eliminates influences of a resolution of a display panel and a design (such as the number of bumps) of a semiconductor chip on an inspection device, achieving general-purpose inspections at low cost.
In the above-mentioned inspection technique, a lighting inspecting circuit including a plurality of inspection semiconductor switching elements or the like has been located in a semiconductor chip mounting region including the semiconductor chip mounted therein. However, the semiconductor chip mounting region needs to be reduced in size with miniaturization of the semiconductor chip and a narrow frame of the display panel, so that the lighting inspecting circuit has conceivably been divided into a plurality thereof located in a region except for the semiconductor chip mounting region (see Japanese Patent Application Laid-Open No. 11-316389 (1999), for example).
In recent times, while a high resolution of the display panel and a high density of the semiconductor chips result in miniaturization of the mounting terminals of the semiconductor chips and the inspection terminals disposed around the mounting terminals, the intervals between the mounting terminals and the inspection terminals have had a tendency to become narrow. This makes stable probing difficult. At the same time, manufacturing the probes is also difficult.
Moreover, using the collective lighting inspecting circuit of the conventional technology enables to inspect wiring of the display portion, the semiconductor elements, and wiring from the mounting terminals of the semiconductor chips to the display portion regardless of the high resolution of the display panel and the high density of the semiconductor chips, but the lighting state actually needs to be checked. Thus, the inspections need to be performed after steps are advanced to a level that enables display. For example, in a case of a liquid crystal display apparatus, the array substrate and the counter substrate overlap each other, and the liquid crystals need to be sealed therebetween. Therefore, when a defect is found in the array substrate in the collective lighting inspection, the counter substrate, the liquid crystals, and the cost that has been spent in manufacturing are wasted. In this respect, the array inspection for a single array substrate is desired.